SOUTHFIELD, Mich. — It was the summer of 2015, and Roderic Green Sr. and his son Roderic Green Jr., better known as “Roddy,” were scrunched up in the bleachers at Cass Tech High School to take in their first Detroit City FC action. The duo had made the 45-minute trek from their hometown of Commerce to Detroit. Roddy was in the midst of a prep career at nearby Lakeland High School that would end with him becoming the boys soccer program’s all-time leading goal scorer.

The 17-year-old urged his father to make the trip into the city to watch the amateur soccer club after he became familiar with Le Rouge’s product and rabid following from some of his contemporaries. Roddy had recently signed his National Letter of Intent to play Division II soccer at Saginaw Valley State University. More than a handful of his future teammates were on the pitch that evening.

And as Detroit City FC took the field for pregame warmups, several players spotted Roddy...